Improving HZSM-5 resistance to phenolic compounds for the bio-oils/FCC feedstocks co-processing

To study the possibility of using micro-/mesoporous ZSM-5 additives to reduce phenolic compounds additional deactivation, when co-processing phenolic-rich bio-oils with traditional Fluid Catalytic Cracking (FCC) feedstocks, the transformations of methylcyclohexane, n-heptane and n-octane were carried out in presence of phenol and guaiacol over alkali-treated HZSM-5 samples, at 450 °C. The results obtained were compared with those previously found for the parent zeolite. At shorter time-on-stream (TOS), HZSM-5 zeolites treated under less severe conditions showed further resistance to phenol for linear alkanes, while mild alkali treatments were desirable to overcome phenol impact for bulkier hydrocarbons. Despite the improved mesoporosity, all alkali-treated HZSM-5 zeolites revealed preserved shape selectivity. Moreover, it was observed that low to moderate-severity alkali-treated HZSM-5 zeolites are still capable of limiting the larger phenolic molecules deactivating effect. Thus, at the conditions of the FCC process, ZSM-5 zeolite additives with combined micro- and mesoporosity could be favorably used, when working with lignocellulosic biomass-based renewable feedstocks, to decrease phenolic molecules detrimental effect, if the proper alkaline treatment conditions were chosen: low-severity treated ZSM-5 additives to produce high-octane number gasoline and mild-severity treated ZSM-5 additives to enhance the light olefins yield.